Intermediate and microcrystalline wax polybutene-1 resin blends



June zo, 1967 R, A, SIGNORELL. ET AL 3,326,835

INTERMEDIATE AND MICROCRYSTALLINE WAX POLYBUTENE-l RESIN BLENDS FiledSept. 9, 1964 Fly/1X 250 /0 2 A /A/IEPMEDM/'E WAX /fv//E/vr/a/v ATTORNEYUnited States Patent O 3,326,835 INTERMEDIATE AND MICROCRYSTALLINE WAXPOLYBUTENE-l RESIN BLENDS Richard A. Signorelli, Clifton, and Joseph I.Wrozina, Tenafly, NJ., and John J. Kaufman, New Brighton, Pa., assignorsto Allied Chemical Corporation, New York, N.Y., a corporation of NewYork Filed Sept. 9, 1964, Ser. No. 395,205 4 Claims. (Cl. 260-28.5)

This invention relates to petroleum fwax compositions and moreparticularly to petroleum wax coating compositions widely used informing protective coatings for wrapping paper and paperboard in theproduction of low-cost cartons for liquids.

Petroleum wax is deficient in several properties such as creased barrierproperties, hardness, grease resistance, and heat sealing properties.Many additives have been proposed -for blending with petroleum Wax toimprove the properties thereof.

The petroleum industry generally classifies petroleum waxes in threemain categories, namely, (1) paraflins; (2) intermediate; and (3)microcrystalline waxes. Other classes of waxes are known such as thescale waxes and slack waxes; these are low-cost crude waxes. Thisinvention is concerned with the upgrading of the intermediate andmicrocrystalline waxes, which, as noted, are distinct, well-known gradesof refined waxes distinguishable from the parains and also the crude orlow-cost waxes such as the scale and :slack waxes. The paraffins arepredominantly the normal paraflins, i.e., straight chain saturatedhydrocarbons lwith minor amounts of isoparaflins. The microcrystallinewaxes are predominantly cyclic saturated hydrocarbons (naphthenes) andiso parati-ins. The intermediate waxes are blends or mixtures ofparaffin and microcrystalline waxes. In Table I below is given theranges of certain physical and .chemical properties of these threeclasses of waxes.

In Table II below is given physical and chemical properties of threetypical commercial waxes, one from each of these three classes.

TABLE II Inter- Micro- Property Paraflins mediate crystaline Gravity,ASTM D-287, API 41. 3 38. 0 34. 4 Melting Point:

ASTM D-87, F 140.1 156. 2 ASTM D-l27, 156.0 173. 5 on calin Point A 1 gg l 153.5 171.5 Penetration, ASTM D132 At 77 F 14 16 10 At 100 F 40 4230 Flash Point, F 455 515 610 Ultraviolet Absorbtvity at 290 my, ASTMD-2008.. 0.01 0.03 0.23 Iodine Number 0. 4 1. 4 3.2 Molecular Weight 442539 746 Refractive Index 1. 4359 1. 4434 1. 4562 Distillation, VacuumCorrected to 760 mm. Hg, 5% Point, F.-- 804 861 967 Patented June 20,1967 The upgrading of waxes by the addition of additives thereto has.sought to improve the creased barrier properties of the coatedmaterial. The property of a coating wax employed for example in thecoating of paper, and paperboard, in the manufacture of food wrappersand paper cartons, to minimize passage of moisture vapor through thecreased or folded coated paper and paperboard is a most important factorin the commercial acceptance of that coating wax. A standard test widelyused in the wax coating art for measuring this property is the creasedmoisture vapor transmission rate (referred to herein as creased WVTR).This test is described in TAPPI 465 creased WVTR. Briefly, it involvesthe determination of the weight of water vapor in grams ywhich passes in24 hours through square inches of accordian pleated test samplecontaining the specified weight of coating. All values herein forcreased WVTR are determined by this test procedure carried out at 100 F.and 95% RH (relative humidity), are tr-uly comparative because the sameweight of coating was applied to all test samples (15 pounds per 3000square feet), and are given in all cases in grams per 100 square inchesfor a 24 hour test period.

Among other properties sought to be improved by the addition ofadditives to the wax are the sealing strength of the wax coating and itsgrease resistance. Sealing strength values are determined by thestandard Socony-Vacuum Seal Tester. Samples are pulled at 3 in./min.with a 100 g. load. The values given are the weight in grams required topull apart two coated specimens which are sealed together under thepredetermined temperature, pressure and dwell time specified in the testprocedure. In the case-of the test results given in the specificationthe test specimens were each rectangular, l2 inches along, 2 incheswide, arranged in superimposed relation with a l inch seal at atemperature of 20G-250 F., pressure of 6-10 p.s.i.g. for a dwell ltimeof i-LS minutes.

Grease resistance is a measure of the time required for a drop of thespecified grease to penetrate through the coated uncreased testspecimen. The grease used in the test results given herein was WessonOil applied at ambient temperatures and maintained at F. until failureof the coating.

It isa principal object of this invention to upgrade intermediate andmicrocrystalline waxes with particular reference to i-mproving theircreased WVTR, heat sealing properties and grease resistance.

Other objects and advantages of this invention will be apparent from thefollowing detailed description thereof.

In accordance with this invention intermediate and microcrystallinewaxes are ugraded by blending therewith from 10% to 40%, preferably 15%to 25%, based on the weight of the coating material (wax pluspolybutene-l resin) of a polybutene-l resin having a molecular weight offrom 100,000 to 300,000, preferably 100,000 to 200,000, and an isotacticcontent of from 50% to 75%, preferably 60% to 70%. Thus this inventioninvolves wax coating compositions consisting essentially of intermediateor microcrystalline waxes blended with from 10% to 40%, preferably 10%to 25% of the aforesaid polybutene-l resins.

In this specificati-on all percentages are given on a weight basis.

The wax coating compositions of this invention have outstandingly goodcreased WVTR values. For example, in the case of an intermediate wax ofF. melting point having a creased WV IR of 6.0, the blending with suchwax of 25% polybutene-l having an isotacticity of from 65-70% and amolecular weight of 150,000 to 190,- 000 reduced the creased WV IR valueto 0.5. The irnprovement in creased WVTR values is significantly betterthan with commercial additives for waxesincluding the ethylene vinylacetate copolymers (Elvax 250 and Elvax 420). Furthermore the wax blendsof this invention have good heat seal strength, good grease resistanceand generally better overall properties than the base wax and the basewax with other additives such as polyethylene, polypropylene and evenwith polybutene-l resins not having the molecular weight andisotacticity hereinabove given for the polybutene-l resins blended withthe intermediate and `microcrystalline waxes.

The discovery that the .blending of the polybutene-l resin having themolecularweight and isotacticity herein disclosed materially improvesthe creased WV lR values and other properties of the base intermediate4and microcrystalline wax is indeed surprising and unobvious. Table IIIwhich follows gives a comparison of the creased WVTR values obtained byblending in the proportions indicated polybutene-l resin having amolecular weight of 190,000 and an isotactic content of 68% withparaffin, intermediate and microcrystalline waxes, substantially thesame as the three typical commercial waxes the properties of which aregiven in Table III.

While the blending of of this polybutene resin resulted in an increasein the creased WVTR value for the paraffin wax from 15.5 to 16.8 it gavea decrease from`5.8 to 5.6 in the case of the 'inter-mediate wax. Theblending of of this polybutene-l resin with the paraffin gave a decreasefrom 15.5 to 12.6 (an improvement of about 20% based on the 15.5 valueof the base wax), whereas the decrease for the intermediate wax was from5.8 to 1.3 (an improvement of about 80%) and the decrease for themicrocrystalline wax was from 9.8 to 1.2 (an improvement of about 88%).Blends of isotactic polybutene-l with parain wax are. more fullydescribed -in our co-pending application Serial No. 395,204, tiled Sept.9, 1964.

In this specification, the expression isotactic is used in itsconventional sense to mean the material in the polymer remaining afterextraction with diethyl ether; the isotactic material is substantiallyinsoluble in hexane Iand naphtha. The diethyl ether extraction removesthe amorphous or atactic material (which is the material soluble inhexane and naphtha) and leaves a polymer containing the isotac-ticmaterial.

The polybutene-l resin employed in forming the wax blends of the presentinvention can be prepared by polymerizing butene-l using a Ziegler typecatalyst and conducting the polymerization under conditions to produce apolymer having the desired isotactic content of from 50%l to 75% anddesired molecular weight of from 100,000'to 300,000. Any of the knownZiegler catalysts can be used; Vfor example, catalysts obtained byreaction between compounds of metals of Group IV-A (titanium, zirconium,hafnium or thorium), V-A (vanadium, columbiu'm or tantalurn), VI-A(chromium, molybdenum, tungsten or uranium) with alkyl compounds ofaluminum a or a metal of Group II (beryllium, magnesium, calcium,

strontium, barium, zinc or cadmium). Polybutene produced bypolymerization using stereospecic catalysts such as CrO3 or SiOz-AlgOasupport or a catalystkconsisting of a promoted M003 may also be used. Inall cases the polymerization must be timed and moderated Ato produce ;apolybutene-l having the desired molecular weight and isotactic content.Hydrogen can be introduced into the polymerization reaction mixture tocontrol the molecular weight and percent isotacticity. Polybutene-lpolymers having an isotactic content of from 50% to 75 and a molecularweight of from 100,000 to 300,000 produced by any known procedure can beused.

Polybutene-l resins having the above noted isotactic contents andmolecular weights blend readily with the intermediate andmicrocrystalline waxes.

The blending of polybutene-l with the intermediate or microcrystallinewax can be effected in any known or desired manner. A typical procedurefor effecting such blending is described below.

A three-necked ask equipped with an electric drive stirrer, athermometer, and a nitrogen inlet tube is charged with a measured amountof the wax. The Wax is heated under nitrogen with moderate stirringuntil a clear liquid results. To the melted wax is added a charge of thepolybutene-l resin having the molecular weight and is-otacticity and inamount all as herein disclosed. The mixture is heated to a temperatureabove the melting point of the wax and stirred to assist solution. Themixture can be maintained under a continuous blanket of nitrogen `duringthe heating and stirring, if desired, and particularly when the heatingis carried out under higher temperatures than C. The polybutene-l chargeis completely dissolved in the wax -in approximately onehalf hour; thisis evident upon visual inspection. Desirably, however, heating of theblend is continued for an additional one-quarter hour to insure completedissolution of the resin in the wax. The blend is thereupon allowed tocool to( ambient temperature.

In the drawing, FIGURE 1 is a graph showing the creased WVTR plottedagainst the precent concentration of two polybutene resins, one having amolecular weight of 150,000 and an isotactic content of 64% (hereinafterreferred to as PB-l) and the other a molecular weight of 190,000 and anisotactic content of 68% (hereinafter referred to as PB-Z). In thisgraph line A shows the creased WVTR for the base wax, an intermediatewax having the properties of the typical intermediate wlax of Table II.Curve B is the ygraph for blends of this intermediate wax with bothpolybutene-l resins; the creased WVTR values for 4blends with bothresins are substantially the same. Line C is the graph for blends of theintermediae wax with an ethylene vinyl acetate copolymer (Elvax 250). Itwill be noted that at concentrations of 15%, the creased WVTR value forthe Elvax wax blend is appreciably greater than that for the base waxwhereas the blends with polybutene resin have creased WVTR values ofabout 3 as compared with 5 for the base wax. At 20% concentration thecreased WVTR value for the Elv\ax wax blend is about 6 and for thepolybutene resin wax blends is about 1.

FIGURE 2 is a graph showing the creased WVTR values plotted againstpercent concentration for (l) the base wax, an intermediate Wax; (2) apolybutene-l intermediate wax blend of this invention in which thepolybutene-l resin is PB-2; (3) lan ethylene vinyl acetate copolymerhaving a vinyl acetate content of 28% (Elvax 250); and (4) a secondethylene vinyl acetate co-polymer having a vinyl acetate content ofabout 18% (Elvax 420). The marked and surprising improvement in creasedWV IR effected in the base intermediate wax by blending therewith thepolybutene-l resins herein disclosed as compared with Elvax is evidentfrom FIGURE 2.

In Table IV which follows is given the comparative creased WVTR valuesfor a microcrystalline wax, substantially the same as the typicalmicrocrystalline wax the properties of which are given in Table IIabove, blended with polybutene resins PB-1 and PB-Z and for comparativepurposes the creased WVTR values of blends of the same microcrystallinewax with an ethylene vinyl acetate copolymer (Elvax 250). The creasedWVTR Value of the base microcrystalline wax was 9.8.

Table V which follows gives the Sealing Strength values for blends ofintermediate `and mirocrystalline waxes with PB-l and PB-2 resins at 20%and 25 concentrations. The sealing strength of the base intermediate waxwas 27 and that of the base microcrystalline wax was 150.

TABLE V Sealing strength Blend: g./ in. width Intermediate 20% PB-l 139Intermediate 25% PB-Z 167 1 tear seal Microcrystalline 20% PB-l 170Microcrystalline 25% PB-2 220 1 tear seal 1 Indicates the coated papertears, i.e., the seal is so strong the paper tears before or at thepoint where the weight is large enough to break the seal.

Table VI which follows gives the grease resistance of blends ofintermediate Wax with PB-l and PB-2 in concentration of and 20%. Thistest was carried out on uncreased paper with Wesson Oil applied atambient temperatures and maintained at 105 F,

TABLE VI Blend Blend Time for Grease Percent Percent To Penetrate, le.,PB-l PB-Z Failure in Hours The time for the base wax was 1 hour. Thusthis test shows a marked improvement in grease resistance properties ofthe blends of this invention as compared with the base Wax.

Examples of this invention have been give in the above including thetables which include comparative data demonstrating the improvements increased WVTR values and sealing strength values embodied in the blendsof intermediate and microcrystalline wax with polybutene-l resins havinga molecular weight of from 100,- 000 to 300,000 and an isotactic contentof from 50% to 75% as compared with Iblends of the same base wax withknown commercial additives, namely the ethylene polyvinyl acetatecopolymers.

The wax blends embodying the present invention are eminentlysatisfactory for use in existing coating equipment. They can be employedin all lields Where wax coatings of superior creased barrier properties,heat seal strength, or good grease resistance nd application. The blendsof this invention, in the molten state, can be applied by known coatingtechniques to foil, parchment, kraft, glassine, chipboard and otherpaper stocks to produce packaging materials having an attractive glossand exceptionally good creased vapor barrier.

10 Since certain changes in the petroleum waX polybutene- 1 blendsembodying this invention can be made without departing from the scope ofthis invention, it is intended that all matter contained in thedescription shall be interpreted as illustrative and not in a limitingsense.

15 What is claimed is:

1. A petroleum wax blend consisting essentially of a petroleum wax fromthe group consisting of intermediate Wax distilling within thetemperature range of about S-900 F. and microcrystalline wax distillingwithin the 2O temperature range of about 950-1050" F. and from 10% to40% by weight of a polybutene-l resin having a molecular weight of from100,000 to 3000,000 and an isotactic content of from 50% to 75 byweight, said blend having creased Water vapor transmission rate lessthan that of 25 the petroleum Wax.

2. The petroleum wax blend of claim 1 in which the polybutene-l resinhas a molecular weight of from 100,000 to 200,000 .and an isotactccontent of from 60% to 70% by weight.

3. A petroleum wax blend of improved creased resistance to transmissionof water vapor therethrough and improved heat sealability which consistsessentially of an intermediate wax blended with from 15% to 25 by weightof a polybutene-l resin having a molecular weight of from 100,000 to200,000 and an isotactic content of from 60% to 70% by Weight.

' 4. A petroleum wax blend of improved creased :resistance totransmission of water vapor therethrough and improved heat scalabilitywhich consists essentially of a 40 microcrystalline wax blended withfrom 15 to 25 by weight of a polybutene-l resin having a molecularWeight of from 100,000 to 200,000 land an isotactic content of from 60%to 70% by weight.

References Cited UNITED STATES PATENTS 2,691,647 10/1954 Field et al.2,824,089 2/ 1958 Peters et al. 260-88.1 2,932,633 4/1960 Iuveland et al26o-94.9

FOREIGN PATENTS 849,389 9/1960 Great Britain.

r MORRIS LIEBMAN, Primary Examiner'.

B. A. AMERNICK, Assistant Examiner.

1. A PETROLEUM WAX BLEND CONSISTING ESSENTIALLY OF A PETROLEUM WAX FROMTHE GROUP CONSISTING OF INTERMEDIATE WAX DISTILLING WITHIN THETEMPERATURE RANGE OF ABOUT 825-900*;. AND MICROCRYSTALLINE WAXDISTILLING WITHIN THE TEMPERATURE RANGE OF ABOUT 950-1050*F. AND FROM10% TO 40% BY WEIGHT OF POLYBUTENE-1 RESIN HAVING A MOLECULAR WEIGHT OFFROM 100,000 TO 300,000 AND AN ISOTACTIC CONTENT OF FROM 50% TO 75% BYWEIGHT, SAID BLEND HAVING CREASED WATER VAPOR TRANSMISSION RATE LESSTHAN THAT OF THE PETROLEUM WAX.